The Global Multi-Resolution Topography (GMRT) synthesis is a multi-resolutional compilation of edited multibeam sonar data collected by scientists and institutions worldwide, that is reviewed, processed and gridded by the GMRT Team and merged into a single continuously updated compilation of global elevation data. The synthesis began in 1992 as the Ridge Multibeam Synthesis (RMBS), was expanded to include multibeam bathymetry data from the Southern Ocean, and now includes bathymetry from throughout the global and coastal oceans. GMRT is included in the ocean basemap in Google Earth (since June 2011) and the GEBCO 2014 compilation.